It has been proposed to use charge coupled devices (CCDs) and other types of solid state detectors for dental and other medical applications using X-ray irradiation to examine structural features of a patient. The CCD replaces the film used in previous systems and enables real-time imaging to be achieved together with a more controlled lower dosage of X-rays for a given exposure.
In one known arrangement, a CCD is used intra-orally and is electrically connected to an X-ray source. When the X-ray source is energized, a start signal is transmitted along the connecting wire to the CCD and to its control circuitry to begin image acquisition and readout. In other arrangements, the X-ray source and CCD have no physical connection. A supplementary sensor is arranged close to the imaging area of the CCD to detect the onset of X-ray energy. On detection of the incident X-ray energy, the sensor sends a signal to the CCD control circuitry to cause imaging to begin.
In another arrangement, the CCD is continually read-out prior to irradiation by X-rays. A signal derived from the CCD is compared with a reference level. If it exceeds the reference level, the image acquisition phase of the CCD operation is initiated.
The present invention seeks to provide an improved imaging apparatus which is particularly advantageously used for dental X-ray diagnosis where the imager device is located intra-orally. The present invention may also be used in other medical or diagnostic applications and could also be advantageously employed for non-medical applications.